Transient Local Injury Current in Right Ventricular Electrogram After Implantable Cardioverter-Defibrillator Shock Predicts Heart Failure Progression

Abstract

Objectives This study aimed to identify an early marker of functional impairment after an ICD shock as a predictor of heart failure progression. Background The ICD population has substantial risk of death due to progressive pump failure. Methods Near field (NF) bipolar right ventricular (RV) electrograms (EGMs) during induced ventricular fibrillation (VF) and 10 seconds after rescue ICD shock were analyzed in 310 patients (mean age 59±14.5 years, 219 male [71%]) with structural heart disease, NYHA class I–III, and implanted with a single- or dual-chamber Medtronic ICD for primary (245 patients, 79%) or secondary prevention of sudden cardiac arrest. A local injury current (LIC) on NF RV EGM was defined as a deviation of EGM potential ≥1 mV or ≥15% of the preceding R wave peak-to-peak amplitude. Results During mean follow-up of 29.3±15.0 months, the combined endpoint of death or hospitalization due to CHF exacerbation was documented in 40 patients (12.9%, or 5.3% per person-year of follow-up). LIC was observed in 106 patients. In multivariate risk analysis, after adjustment for baseline prognostic factors (ejection fraction, history of atrial fibrillation, diabetes mellitus) and appropriate ICD shocks during follow-up, patients with observed LIC after induced VF rescue ICD shock at ICD implantation were more likely to die or to be hospitalized (hazard ratio, 2.69; 95%CI, 1.41 –5.14; P=0.003). Conclusions Transient LIC on bipolar NF RV EGM after induced VF rescue ICD shock is associated with increased risk of CHF progression, future hospitalizations due to CHF exacerbation, and subsequent heart failure death.

Efficacy of Long Detection Interval Implantable Cardioverter-Defibrillator Settings in Secondary Prevention Population

“…By prolonging the time of detection to longer settings, it is not surprising that fewer inappropriate therapies were delivered; previous studies have shown that most inappropriate therapies are determined by high-rate conducted atrial arrhythmias or lead noises, both of which are influenced favorably by a longer NID. [7][8][9][10][11][12][13][14][15][16] Nevertheless, in terms of the recent hypothesis of a possible association between unnecessary ATPs and increased risk of adverse events in PP, the present data provide a clear indication for a programming strategy that can safely reduce inappropriate therapies in SP patients as well.…”

Efficacy of Anti-Tachycardia Pacing for Terminating Fast Ventricular Tachycardia in Japanese Implantable Cardioverter Defibrillator Patients

“…14 Another study showed that a local injury current on near-field bipolar right ventricular electrogram (EGM) after induced ventricular fibrillation (VF) rescue ICD shock is associated with increased risk of congestive heart failure (CHF) progression, future hospitalizations due to CHF exacerbation, and subsequent heart failure death. 15 These results showed that ICD shock was associated with a markedly increased risk of death. Using anti-tachycardia pacing (ATP) as the first therapy for fast ventricular rhythms has been shown to minimize ICD shock and their potentially detrimental effects.…”

The Implantable Cardioverter-Defibrillator Minimalist

“…34 The instantaneous emergence of a transient local injury current on the right ventricular electrogram (EGM) after an induced VF shock, not present during the immediately preceding sinus rhythm, identified patients who were at Ϸ2.5 times increased risk of HF and death following spontaneous VTA shocks. 37 Two related observations raise concern for mortality effects of shocks. First, inappropriate shocks increase mortality risk by 2 to 4 times.…”